CN116893541A

CN116893541A - Beam direction control element, display device and method for manufacturing beam direction control element

Info

Publication number: CN116893541A
Application number: CN202310259343.9A
Authority: CN
Inventors: 城川政宜; 冈本守
Original assignee: Tianma Japan Ltd
Current assignee: Tianma Japan Ltd
Priority date: 2022-03-31
Filing date: 2023-03-17
Publication date: 2023-10-17

Abstract

Disclosed are a beam direction control element, a display device, and a method for manufacturing the beam direction control element, the beam direction control element including: the liquid crystal display device includes a first light-transmitting substrate, a second light-transmitting substrate, a light-transmitting region interposed between the first light-transmitting substrate and the second light-transmitting substrate, a light-absorbing region located between the light-transmitting regions, a light-transmitting dispersion medium enclosed in the light-absorbing region, and electrophoretic particles dispersed in the light-transmitting dispersion medium. The light transmissive region includes a first light transmissive region extending from the first light transmissive substrate toward the second light transmissive substrate, and a second light transmissive region extending from the first light transmissive region toward the second light transmissive substrate. The first light transmission region has a height lower than a height of the second light transmission region, and the first light transmission region has a width wider than a width of the second light transmission region.

Description

Beam direction control element, display device and method for manufacturing beam direction control element

Cross Reference to Related Applications

The present application claims the benefit of Japanese patent application No. 2022-058156 filed on 3.31 of 2022 and Japanese patent application No. 2022-191434 filed on 11.30 of 2022, the disclosures of which are incorporated herein by reference.

Technical Field

The present application relates generally to a beam steering element, a display device and a method for manufacturing a beam steering element.

Background

A beam direction control element that controls an emission range of transmitted light is known. For example, japanese patent No. 6443691 discloses an optical element comprising: the display device includes first and second transparent substrates disposed with respective main surfaces facing each other, a conductive light-shielding pattern disposed on the first transparent substrate, a transparent conductive film disposed on the second transparent substrate, a plurality of light-transmitting regions disposed on the first transparent substrate, and an electrophoretic element disposed between adjacent light-transmitting regions and including light-shielding electrophoretic particles and a transmissive dispersant. In the optical element disclosed in japanese patent No. 6443691, by adjusting the potential difference between the conductive light-shielding pattern and the transparent conductive film, the dispersion state of the electrophoretic particles is changed, resulting in a change in the emission range of light transmitted through the light-transmitting region and the dispersant.

In the optical element disclosed in japanese patent No. 6443691, a wide field-of-view state (wide emission range) is achieved by focusing the electrophoretic particles in the vicinity of the conductive light-shielding pattern. In the wide field state, it is necessary to further increase the transmittance of the optical element. In order to further increase the transmittance of the optical element in the wide field state, the aperture ratio of the optical element is increased in the wide field state by narrowing the region where the electrophoretic particles are concentrated (i.e., the interval between the light transmission regions).

On the other hand, in order to change the light emission range, it is also necessary to form the light transmission region with a high aspect ratio. In japanese patent No. 6443691, since the light transmitting region is formed of a resin (photoresist) having photosensitivity, it is difficult to form the light transmitting region having a high aspect ratio at narrow intervals.

The present disclosure is made to solve the above-described problems, and an object of the present disclosure is to provide a beam direction control element having high transmittance in a state where an angular distribution of emitted light is wide, a display device, and a method of manufacturing the beam direction control element.

Disclosure of Invention

In order to achieve the above object, a beam direction control element according to a first aspect includes:

a first light transmissive substrate including a first light transmissive electrode on a main surface,

a second light-transmitting substrate facing the first light-transmitting substrate and including a second light-transmitting electrode on a main surface facing the main surface of the first light-transmitting substrate,

a plurality of light-transmitting regions arranged in a predetermined direction and interposed between the first light-transmitting substrate and the second light-transmitting substrate,

a plurality of light absorbing regions located between the light transmitting regions,

a light-transmitting dispersion medium enclosed in the light-absorbing region; and

The light-absorbing electrophoretic particles are dispersed in a light-transmitting dispersion medium and have a dispersed state that is changed by an applied voltage, wherein

Each light transmitting region includes a first light transmitting region extending perpendicularly to the main surface of the first light transmitting substrate from the main surface of the first light transmitting substrate toward the second light transmitting substrate, and a second light transmitting region extending perpendicularly to the main surface of the first light transmitting substrate from the upper surface of the first light transmitting region toward the second light transmitting substrate,

each light absorbing region includes a first light absorbing region located between the first light transmitting regions and a second light absorbing region located between the second light transmitting regions,

the first light transmission region has a lower height from the main surface of the first light transmission substrate than the second light transmission region, and

the width of the first light-transmitting region is wider than the width of the second light-transmitting region when viewed in a cross section including a predetermined direction and perpendicular to the main surface of the first light-transmitting substrate.

The display device according to the second aspect includes:

beam direction control element, and

the display panel is provided with a display screen,

wherein the beam direction control element is disposed on a display surface of the display panel.

The display device according to the third aspect includes:

a beam direction control element for controlling the direction of the light beam,

transmissive liquid crystal display panel, and

a backlight disposed on an opposite side of a display surface of the transmissive liquid crystal display panel and providing light to the transmissive liquid crystal display panel,

wherein the beam direction control element is disposed between the transmissive liquid crystal display panel and the backlight.

The method for manufacturing a beam direction control element according to the fourth aspect includes:

preparing a mold including a mold substrate, a plurality of first pillars disposed on the main surface perpendicularly to the main surface of the mold substrate and arranged in a predetermined direction, and a second pillar disposed on an upper surface of each of the plurality of first pillars perpendicularly to the main surface of the mold substrate,

the mold is filled with a light-transmitting resin,

pressing a main surface of a first light-transmitting substrate against the second support posts and the light-transmitting resin exposed from between the second support posts, the first light-transmitting substrate including a first light-transmitting electrode on the main surface of the first light-transmitting substrate,

curing the light transmitting resin pressed against the main surface of the first light transmitting substrate,

demolding the mold from the cured light-transmitting resin, and forming a plurality of light-transmitting layers on the main surface of the first light-transmitting substrate, the plurality of light-transmitting layers including a first light-transmitting layer having a shape corresponding to a shape of a space between adjacent second pillars, and a second light-transmitting layer having a shape corresponding to a shape of a space between adjacent first pillars,

Pressing a second light-transmitting substrate facing the first light-transmitting substrate onto the plurality of light-transmitting layers, the second light-transmitting substrate including a second light-transmitting electrode on a major surface facing the major surface of the first light-transmitting substrate, and

filling a light-transmitting dispersion medium including dispersed electrophoretic particles, which absorb light and have a dispersion state changed by an applied voltage, between the light-transmitting layers, wherein

The height of the space between the adjacent second struts is lower than the height of the space between the adjacent first struts, and

the width of the space between adjacent second pillars is wider than the width of the space between adjacent first pillars when viewed in a cross section including a predetermined direction and perpendicular to the main surface of the mold substrate.

The method for manufacturing a beam direction control element according to the fifth aspect includes:

forming a light shielding layer on a main surface of a first light transmitting substrate at predetermined intervals, the first light transmitting substrate including a first light transmitting electrode on the main surface,

stacking a first layer having a predetermined first thickness, which is made of a light-transmitting material having photosensitivity and covers the light-shielding layer, on a main surface of the first light-transmitting substrate,

Exposing the first layer from one side of the first light transmissive substrate,

stacking a second layer having a predetermined second thickness thicker than the predetermined first thickness on the exposed first layer, the second layer being made of a light-transmitting material having photosensitivity,

when viewed in a plan view from one side of the second layer, the region of the second layer located between the light shielding layers is exposed to light with a width narrower than a predetermined interval between the light shielding layers,

developing the exposed first layer and the exposed second layer, and forming a plurality of light transmissive layers on the first main surface of the first light transmissive substrate,

pressing a second light-transmitting substrate facing the first light-transmitting substrate onto the plurality of light-transmitting layers, the second light-transmitting substrate including a second light-transmitting electrode on a major surface facing a major surface of the first light-transmitting substrate, and

a light-transmitting dispersion medium including dispersed electrophoretic particles that absorb light and have a dispersion state that is changed by an applied voltage is filled between the light-transmitting layers.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the disclosure.

According to the present disclosure, since the height of the first light transmission regions is lower than the height of the second light transmission regions and the width of the first light transmission regions is wider than the width of the second light transmission regions, the first light absorption regions located between the first light transmission regions are narrowed in a plan view, so that the transmittance of the beam direction control element in a state where the angular distribution of emitted light is wide can be improved.

Drawings

A more complete understanding of the present application may be obtained when the following detailed description is considered in conjunction with the following drawings, in which:

fig. 1 is a sectional view showing a beam direction control element according to embodiment 1;

fig. 2 is a schematic diagram showing a display device according to embodiment 1;

fig. 3 is a perspective view showing a first light transmission region, a second light transmission region, a first light absorption region, and a second light absorption region according to embodiment 1;

fig. 4 is a schematic diagram showing a narrow field-of-view mode according to embodiment 1;

fig. 5 is a view showing an angular distribution of emitted light in the beam direction control element according to embodiment 1 on a plane parallel to the XZ plane;

fig. 6 is a schematic diagram showing a first wide field-of-view mode according to embodiment 1;

fig. 7 is a plan view showing a beam direction control element in the first wide field mode according to embodiment 1;

fig. 8 is a flowchart showing a method for manufacturing a beam direction control element according to embodiment 1;

fig. 9 is a schematic diagram showing a mold according to embodiment 1;

fig. 10 is a schematic view showing a mold and a light-transmitting resin according to embodiment 1;

fig. 11 is a schematic view showing a mold, a light-transmitting resin, and a first light-transmitting substrate according to embodiment 1;

Fig. 12 is a schematic view showing a first light-transmitting substrate and a light-transmitting layer according to embodiment 1;

fig. 13 is a schematic view showing a first light-transmitting substrate, a light-transmitting layer, and a second light-transmitting substrate according to embodiment 1;

fig. 14 is a schematic diagram showing a second wide field-of-view mode according to embodiment 2;

fig. 15 is a view showing an angular distribution of emitted light in a beam direction control element according to embodiment 2 on a plane parallel to the XZ plane;

fig. 16 is a sectional view showing a beam direction control element according to embodiment 3;

fig. 17 is a sectional view showing a beam direction control element according to embodiment 4;

FIG. 18 is a schematic diagram showing the maximum emission angle according to embodiment 5;

fig. 19 is a schematic view showing the height and maximum emission angle of the second light transmission region according to embodiment 5;

fig. 20 is a flowchart showing a method for manufacturing a beam direction control element according to embodiment 6;

fig. 21 is a schematic view showing a light shielding layer according to embodiment 6;

fig. 22 is a schematic diagram showing a first layer according to embodiment 6;

fig. 23 is a schematic diagram showing exposure of the first layer according to embodiment 6;

fig. 24 is a schematic diagram showing a second layer according to embodiment 6;

Fig. 25 is a schematic diagram showing exposure of a second layer according to embodiment 6;

fig. 26 is a schematic diagram showing a first light-transmitting substrate and a light-transmitting layer according to embodiment 6;

fig. 27 is a schematic diagram showing a beam direction control element according to a modification;

fig. 28 is a schematic view showing a first light transmission region according to a modification;

fig. 29 is a schematic view showing a first light transmission region according to a modification;

fig. 30 is a schematic view showing a first light transmission region according to a modification;

fig. 31 is a schematic view for explaining the remaining of the electrophoretic particles;

fig. 32 is a schematic view showing a first light transmission region according to a modification;

fig. 33 is a schematic view showing a first light transmission region according to a modification;

fig. 34 is a schematic view showing a first light transmission region according to a modification;

fig. 35 is a schematic diagram showing a display device according to a modification; and

fig. 36 is a schematic diagram showing a display device according to a modification.

Detailed Description

Hereinafter, a beam direction control element and a display device according to embodiments are described with reference to the accompanying drawings.

Example 1

The beam direction control element 100 and the display device 300 according to the present embodiment are described with reference to fig. 1 to 13. As shown in fig. 1, the beam direction control element 100 includes a first light transmissive substrate 10, a second light transmissive substrate 20, a light transmissive region 30, and a light absorbing region 40. The light-transmitting dispersion medium 52 and the electrophoretic particles 54 are enclosed in the light-absorbing region 40. Each light-transmitting region 30 includes a first light-transmitting region 32 and a second light-transmitting region 34. Each light absorbing region 40 includes a first light absorbing region 42 and a second light absorbing region 44. In the beam direction control element 100, a voltage applied to the electrophoretic particles 54 from an external power source (not shown) changes the dispersion state of the electrophoretic particles 54 in the light-transmitting dispersion medium 52, thereby changing the angular distribution of the emitted light emitted from the beam direction control element 100. For ease of understanding, in this specification, it is assumed that the right direction (right direction on the paper) of the beam direction control element 100 in fig. 1 is the +x direction, the upper direction (upper direction on the paper) thereof is the +z direction, and the directions perpendicular to the +x direction and the +z direction (depth direction on the paper) are the +y direction, and the following description is given. The X direction is also referred to as the horizontal direction, and the Z direction is also referred to as the vertical direction.

As shown in fig. 2, the beam direction control element 100 constitutes a display device 300 together with the display panel 210. The display device 300 is mounted on a smart phone, a laptop computer, a vehicle, an information display, or the like. The display panel 210 displays characters, images, and the like. The display panel 210 is a liquid crystal display panel, an organic Electroluminescence (EL) display panel, a micro Light Emitting Diode (LED) display panel, or the like.

The beam direction control element 100 controls the angular distribution of light (angular distribution of emitted light) emitted from the display panel 210 and passing through the beam direction control unit 100. The beam direction control element 100 is disposed on the display surface of the display panel 210.

Returning now to fig. 1, the first light transmissive substrate 10 of the beam direction control element 100 transmits visible light. Examples of the first light-transmitting substrate 10 include a flat glass substrate. The first light transmissive substrate 10 includes a first light transmissive electrode 12 on a first major surface 10a thereof. In the present embodiment, the first light-transmitting electrode 12 is made of Indium Tin Oxide (ITO) on the entire surface of the first main surface 10 a. An insulating layer (not shown) is provided on the first light transmissive electrode 12. The insulating layer being made of, for example, silicon oxide (SiO ₂ ) Is prepared.

The second light-transmitting substrate 20 of the beam direction control element 100 transmits visible light as the first light-transmitting substrate 10. The second light-transmitting substrate 20 is, for example, a flat glass substrate. The second light transmissive substrate 20 includes a second light transmissive electrode 22 on a first main surface 20a thereof. The second light-transmitting electrode 22 is made of ITO over the entire surface of the first main surface 20 a. An insulating layer is also provided on the second light transmissive electrode 22.

The second light transmissive substrate 20 faces the first light transmissive substrate 10. In the present embodiment, the first main surface 10a of the first light transmissive substrate 10 and the first main surface 20a of the second light transmissive substrate 20 face each other.

The light transmission region 30 of the beam direction control element 100 is a region transmitting visible light. The light transmissive region 30 is arranged in the X direction and is interposed between the first light transmissive substrate 10 and the second light transmissive substrate 20. The light-transmitting region 30 is, for example, a light-transmitting layer made of a light-transmitting resin. As shown in fig. 1, each light-transmitting region 30 includes a first light-transmitting region 32 and a second light-transmitting region 34. In the present embodiment, the X direction corresponds to a predetermined direction.

The first light-transmitting region 32 is provided on the first main surface 10a of the first light-transmitting substrate 10. As shown in fig. 1 and 3, the first light-transmitting region 32 has a rectangular parallelepiped shape extending perpendicular to the first main surface 10a of the first light-transmitting substrate 10 (i.e., extending in the +z direction) from the first main surface 10a of the first light-transmitting substrate 10 toward the second light-transmitting substrate 20. The first light transmission region 32 also extends in the Y direction (depth direction). The first light transmission regions 32 are arranged at intervals corresponding to a width D3 of the first light absorption region 42, which will be described below, in the X direction. The interval between the first light transmission regions 32 refers to an interval between side surfaces of adjacent first light transmission regions 32.

The height H1 of the first light-transmitting region 32 from the first main surface 10a of the first light-transmitting substrate 10 is lower than the height H2 of the second light-transmitting region 34, which will be described below. The width D1 of the first light transmission region 32 is wider than the width D2 of the second light transmission region 34 to be described below when viewed in a section including an XZ section, i.e., an X direction (predetermined direction) and perpendicular to the first main surface 10a of the first light transmission substrate 10 and the first main surface 20a of the second light transmission substrate 20. A more specific configuration of the first light transmission region 32 will be described below. The height H1 of the first light-transmitting region 32 from the first main surface 10a of the first light-transmitting substrate 10 is also referred to as the height H1 of the first light-transmitting region 32.

In the present embodiment, since the width D1 of the first light transmission region 32 is wider, the adhesiveness between the first light transmission substrate 10 and the first light transmission region 32 (light transmission layer) is improved. This prevents the light-transmitting region 30 (light-transmitting layer) from peeling from the first light-transmitting substrate 10, thereby improving the durability of the beam direction control element 100.

The second light transmission region 34 has a rectangular parallelepiped shape extending perpendicularly to the first main surface 10a of the first light transmission substrate 10 from the upper surface (+z-side surface) 32a of the first light transmission region 32 toward the second light transmission substrate 20. The second light transmission region 34 also extends in the Y direction. The second light transmitting regions 34 are arranged at intervals corresponding to a width D4 of a second light absorbing region 44 to be described below in the X direction. The height H2 of the second light transmission region 34 from the upper surface 32a of the first light transmission region 32 is higher than the height H1 of the first light transmission region 32. The width D2 of the second light transmission region 34 is narrower than the width D1 of the first light transmission region 32 when viewed in XZ cross section. A more specific configuration of the second light transmission region 34 is described below. The interval between the second light transmission regions 34 refers to an interval between side surfaces of adjacent second light transmission regions 34. The height H2 of the second light transmission region 34 from the upper surface 32a of the first light transmission region 32 is also referred to as the height H2 of the second light transmission region 34.

As shown in fig. 1 and 3, the light absorbing region 40 of the beam direction control element 100 is a region between adjacent light transmitting regions 30. Each light absorbing region 40 includes a first light absorbing region 42 and a second light absorbing region 44. As described below, the light absorbing region 40 is formed by forming the light transmitting region 30 on the first main surface 10a of the first light transmitting substrate 10. The first light absorbing region 42 is formed by the adjacent first light transmitting region 32. The second light absorbing region 44 is formed by the adjacent second light transmitting region 34.

The first light absorbing regions 42 are regions between adjacent first light transmitting regions 32. As with the first light-transmitting region 32, the first light-absorbing region 42 extends perpendicularly to the first main surface 10a of the first light-transmitting substrate 10 from the first main surface 10a of the first light-transmitting substrate 10 toward the second light-transmitting substrate 20. The second light absorbing region 44 is a region between adjacent second light transmitting regions 34, and extends perpendicularly to the first main surface 10a of the first light transmitting substrate 10 from the first light absorbing region 42 toward the second light transmitting substrate 20. The first light absorbing region 42 and the second light absorbing region 44 also extend in the Y direction.

In the present embodiment, since the first light absorbing regions 42 are regions between adjacent first light transmitting regions 32, the height of the first light absorbing regions 42 from the first main surface 10a of the first light transmitting substrate 10 is equal to the height H1 of the first light transmitting regions 32 from the first main surface 10a of the first light transmitting substrate 10. Since the second light absorbing region 44 is a region between adjacent second light transmitting regions 34, the height of the second light absorbing region 44 from the upper surface 42a of the first light absorbing region 42 is equal to the height H2 of the second light transmitting region 34 from the upper surface 32a of the first light transmitting region 32. Further, since the height H1 of the first light transmission region 32 is lower than the height H2 of the second light transmission region 34, the height H1 of the first light absorption region 42 is smaller than the height H2 of the second light absorption region 44. The height of the first light absorbing region 42 from the first main surface 10a of the first light transmissive substrate 10 is also referred to as the height H1 of the first light absorbing region 42, and the height of the second light absorbing region 44 from the upper surface 42a of the first light absorbing region 42 is also referred to as the height H2 of the second light absorbing region 44.

The width D1 of the first light transmission region 32 is wider than the width D2 of the second light transmission region 34 when viewed in XZ cross section. Therefore, the width D3 of the first light absorbing region 42 is narrower than the width D4 of the second light absorbing region 44 when viewed in XZ cross section. A more specific configuration of the first light absorbing region 42 and the second light absorbing region 44 is described below.

The light-transmitting dispersion medium 52 of the beam direction control element 100 is enclosed in the light absorbing region 40. The light-transmitting dispersion medium 52 transmits visible light. The light-transmitting dispersion medium 52 disperses the electrophoretic particles 54.

The electrophoretic particles 54 of the beam direction control element 100 are dispersed in the light transmissive dispersion medium 52. The electrophoretic particles 54 absorb visible light. The electrophoretic particles 54 are positively or negatively charged, and the dispersion state of the electrophoretic particles 54 in the light-transmissive dispersion medium 52 is changed by the voltages applied by the first light-transmissive electrode 12 and the second light-transmissive electrode 22. The electrophoretic particles 54 are, for example, charged carbon black particles. In this embodiment, the electrophoretic particles 54 are assumed to be negatively charged.

The light-transmitting dispersion medium 52 and the electrophoretic particles 54 dispersed in the light-transmitting dispersion medium 52 are enclosed in the light-absorbing region 40. Accordingly, the light absorbing region 40 (the first light absorbing region 42 and the second light absorbing region 44) functions as an electrophoretic element together with the first light transmitting electrode 12 and the second light transmitting electrode 22. By controlling the potential V1 of the first light-transmitting electrode 12 and the potential V2 of the second light-transmitting electrode 22, the dispersion state of the electrophoretic particles 54 is changed, thereby allowing the light-absorbing region 40 to function as a light-absorbing layer according to the dispersion state of the electrophoretic particles 54.

The operation of the beam direction control element 100 is described below assuming that a surface light source (uniformly diffused surface light source) 700 having a constant luminance when viewed from any direction is provided on the first light-transmitting substrate 10 side of the beam direction control element 100. The beam direction control element 100 controls the angular distribution of the light 710 incident from the-Z direction and emits the light in the +z direction.

Narrow field of view mode

When the potential V1 of the first light-transmitting electrode 12 and the potential V2 of the second light-transmitting electrode 22 are equal to each other and no voltage is applied to the electrophoretic particles 54, the electrophoretic particles 54 are uniformly dispersed over the entire light-absorbing region 40. In this case, the entire light absorbing region 40 (the first light absorbing region 42 and the second light absorbing region 44) serves as a light absorbing layer. Hereinafter, the above state is referred to as a narrow field of view mode.

Since the first light absorbing region 42 and the second light absorbing region 44 are perpendicular to the first main surface 10a of the first light transmissive substrate 10 when viewed in cross section on the XZ plane, light 710 incident from the surface light source 700 except for light near the +z direction is absorbed in the first light absorbing region 42 and the second light absorbing region 44 in the narrow field of view mode as shown in fig. 4. In the XZ plane, out of the light 710 incident from the surface light source 700, light in the vicinity of +z direction is emitted from the beam direction control element 100. Therefore, when the +x direction is 0 °, +z direction is 90 °, and-X direction is 180 °, on a plane parallel to the XZ plane, the light emitted from the beam direction control element 100 in the narrow field-of-view mode has a narrow angular distribution close to 90 ° (+z direction), as shown in fig. 5.

In a plane parallel to the YZ plane including the first light transmission region 32 and the second light transmission region 34, since the first light transmission region 32 and the second light transmission region 34 extend in the Y direction, light emitted from the beam direction control element 100 in the narrow field-of-view mode has a uniform angular distribution. In the other plane parallel to the YZ plane, since the first light absorbing region 42 and the second light absorbing region 44 extend in the Y direction, the light 710 incident from the surface light source 700 is absorbed in the first light absorbing region 42 and the second light absorbing region 44. The plane parallel to the YZ plane includes the YZ plane.

As described above, the light emitted from the beam direction control element 100 in the narrow field-of-view mode has a narrow angular distribution of approximately 90 ° (+z direction) in a plane parallel to the XZ plane, and has a uniform angular distribution in a plane parallel to the YZ plane including the first light transmission region 32 and the second light transmission region 34. Therefore, in the narrow field-of-view mode, the beam direction control element 100 can limit the viewing angle of the display device 300 in the left-right direction (X direction) to the vicinity of the front (+z direction).

First wide field of view mode

When the potential V1 of the first light-transmitting electrode 12 is made higher than the potential V2 of the second light-transmitting electrode 22 and a predetermined first voltage is applied to the electrophoretic particles 54, the negatively charged electrophoretic particles 54 are collected in the first light-absorbing region 42, and only the first light-absorbing region 42 functions as a light-absorbing layer. Hereinafter, the above state is referred to as a first wide field mode.

In the first wide field of view mode, only the first light absorbing region 42 serves as a light absorbing layer. The height H1 of the first light absorbing region 42 from the first main surface 10a of the first light transmissive substrate 10 is lower than the height H2 of the second light absorbing region 44 from the upper surface 42a of the first light absorbing region 42. Therefore, as shown in fig. 6, when viewed in cross section on the XZ plane, only a part of the incident light 710 having a large angle with respect to the +z direction is absorbed in the first light absorbing region 42, and the other incident light is emitted from the beam direction control element 100, out of the light 710 incident from the surface light source 700. That is, in a plane parallel to the XZ plane, the light emitted from the beam direction control element 100 in the first wide field of view mode has a wide angular distribution, as shown in fig. 5.

In a plane parallel to the YZ plane including the first light transmission region 32 and the second light transmission region 34, since the first light transmission region 32 and the second light transmission region 34 extend in the Y direction, light emitted from the beam direction control element 100 in the first wide field of view mode has a uniform angular distribution. In another plane parallel to the YZ plane, since the first light absorbing region 42 extends in the Y direction, the light 710 incident from the surface light source 700 is absorbed in the first light absorbing region 42.

As described above, the light emitted from the beam direction control element 100 in the first wide field-of-view mode has a wide angular distribution in a plane parallel to the XZ plane, and has a uniform angular distribution in a plane parallel to the YZ plane including the first light transmission region 32 and the second light transmission region 34. Therefore, in the first wide field of view mode, the beam direction control element 100 hardly limits the viewing angle of the display apparatus 300. The first wide field mode refers to a state in which the angular distribution of the emitted light is wide.

A more specific configuration of the first light transmitting region 32, the second light transmitting region 34, the first light absorbing region 42, and the second light absorbing region 44 is described. As an example, the light transmission region 30 is formed such that the height H1 of the first light transmission region 32 is 25 μm, the width D1 of the first light transmission region 32 is 45 μm, the height H2 of the second light transmission region 34 is 120 μm, and the width D2 of the second light transmission region 34 is 40 μm. The light absorbing regions 40 are formed such that the height H1 of the first light absorbing regions 42 is 25 μm, the width D3 of the first light absorbing regions 42 (the interval between the first light transmitting regions 32) is 5 μm, and the width D4 of the second light absorbing regions 44 (the interval between the second light transmitting regions 34) is 10 μm. The height H of the light transmitting region 30 and the light absorbing region 40 from the first main surface 10a of the first light transmitting substrate 10 is 145 μm.

The above-mentioned light absorption region 40 is filled with a light-transmitting dispersion medium 52 comprising, for example, 4wt% of electrophoretic particles 54 having an average particle size of 120 nm. Specifically, when the particle density of the electrophoretic particles 54 is 0.5g/cm3, the maximum packing factor of the electrophoretic particles 54 in the light absorbing region 40 is 71.6% (74% in the most densely packed state), the solvent density of the liquid of the light transmitting dispersion medium 52 is 0.75g/cm3, and the lengths (depths) of the light transmitting region 30 and the light absorbing region 40 in the Y direction are L μm, the first light absorbing region 42 may be packed with the electrophoretic particles 54 whose height H1 (25 μm) reaches 21.8 μm, as shown in the following formula (1).

As shown in fig. 7, when the beam direction control element 100 in the first wide field of view mode having the above configuration is viewed in plan view from the +z direction, the aperture ratio of the beam direction control element 100 in the first wide field of view mode is 90% ((45/50) ×100). On the other hand, when the light absorbing region 40 is formed of only the second light absorbing region 44 (hereinafter, referred to as a comparative example), the aperture ratio of the beam direction control element in the wide field mode is 80% ((40/50) ×100). For ease of understanding, fig. 7 does not show the first light transmissive substrate 10, the second light transmissive substrate 20, and the like.

In the present embodiment, the height H1 of the first light transmission region 32 forming the first light absorption region 42 collecting the electrophoretic particles 54 in the first wide field mode is lower than the height H2 of the second light transmission region 34, and the aspect ratio of the first light transmission regions 32 is small, so that the interval between the first light transmission regions 32 (i.e., the width D3 of the first light absorption region 42) can be easily narrowed. Since the width D1 of the first light transmission region 32 is wider than the width D2 of the second light transmission region 34, the width D3 of the first light absorption region 42 collecting the electrophoretic particles 54 in the first wide field of view mode is narrower than the width D4 of the second light absorption region 44, so that the aperture ratio of the beam direction control element 100 in the first wide field of view mode may be increased as in the above example. Since the aperture ratio in the first wide field mode is high, the transmittance of the beam direction control element 100 in the first wide field mode may be increased as shown in fig. 5.

Next, a method of manufacturing the beam direction control element 100 is described. Fig. 8 is a flowchart showing a method for manufacturing the beam direction control element 100. The method for manufacturing the beam steering element 100 includes: the method includes a step of preparing the mold 400 (step S100), a step of filling the mold 400 with the light-transmitting resin 450 (step S102), a step of pressing the first main surface 10a of the first light-transmitting substrate 10 against the light-transmitting resin 450 exposed from between the second pillars 424 (step S104), a step of curing the light-transmitting resin 450 (step S106), and a step of demolding the mold 400 from the cured light-transmitting resin 450 and forming a plurality of light-transmitting layers 60 on the first main surface 10a of the first light-transmitting substrate 10 (step S108).

The method for manufacturing the beam direction control element 100 further includes a step of press-fitting the second light transmissive substrate 20 onto the plurality of light transmissive layers 60 (step S110), and a step of filling the light transmissive dispersion medium 52 in which the electrophoretic particles 54 are dispersed between the light transmissive layers 60 (step S112).

In step S100, a mold 400 for forming the light transmissive region 30 on the first main surface 10a of the first light transmissive substrate 10 is prepared using a known photolithography technique. The mold 400 includes a mold base 410 and a post 420, as shown in fig. 9. The mold substrate 410 is, for example, a silicon substrate. The pillars 420 are made of chemically amplified photoresist SU-8 (trade name, nippon Kayaku co., ltd.) on the first main surface 410a of the mold substrate 410 by using a known photolithography technique. The shape of the post 420 corresponds to the light absorbing region 40 of the beam direction control element 100. The shape of the space between adjacent pillars 420 corresponds to the shape of the light-transmitting region 30 of the beam-direction control element 100.

Each strut 420 includes a first strut 422 and a second strut 424. The first support posts 422 are disposed on the first main surface 410a of the mold substrate 410 perpendicular to the first main surface 410a, and have a rectangular parallelepiped shape. The first support posts 422 are arranged in the X direction such that a spacing W21 between side surfaces 422a (+x-side surface and-X-side surface) of adjacent first support posts 422 is equal to a width D2 of the second light transmission region 34 of the light beam direction control element 100, and extends in the Z direction and the Y direction. The height H21 of the first support posts 422 from the first main surface 410a of the mold substrate 410 is equal to the height H2 of the second light absorbing region 44 and the second light transmitting region 34. The width D41 of the first support post 422 is equal to the width D4 of the second light absorbing region 44 when viewed in XZ cross section. The shape of the first support posts 422 corresponds to the shape of the second light absorbing region 44 of the beam direction control element 100. The shape of the space 432 between adjacent first support posts 422 corresponds to the shape of the second light transmission region 34 of the beam direction control element 100.

The second support post 424 is provided on an upper surface (+z-side surface) 422b of the first support post 422 perpendicularly to the first main surface 410a, and has a rectangular parallelepiped shape. The second support posts 424 are arranged in the X direction such that the interval W11 between the side surfaces 424a of the adjacent second support posts 422 is equal to the width D1 of the first light transmission region 32 of the beam direction control element 100, and extends in the Z direction and the Y direction. The height H11 of the second support posts 424 from the upper surface 422b of the first support posts 422 is equal to the height H1 of the first light absorbing region 42 and the first light transmitting region 32. The width D31 of the second pillar 424 is equal to the width D3 of the first light absorbing region 42 when viewed in XZ cross section. The shape of the second leg 424 corresponds to the shape of the first light absorbing region 42 of the beam direction control element 100. The shape of the space 434 between adjacent second struts 424 corresponds to the shape of the first light transmissive region 32 of the beam direction control element 100.

In the present embodiment, the height H21 of the first support post 422 is equal to the height H2 of the second light absorbing region 44 and the second light transmitting region 34, and the height H11 of the second support post 424 is equal to the height H1 of the first light absorbing region 42 and the first light transmitting region 32. Since the height H1 of the first light absorbing region 42 and the first light transmitting region 32 is lower than the height H2 of the second light absorbing region 44 and the second light transmitting region 34, the height H11 of the second support posts 424 (i.e., the height of the spaces 434 between adjacent second support posts 422) is lower than the height H21 of the first support posts 422 (i.e., the height of the spaces 432 between adjacent first support posts 422).

The interval W21 between the first support posts 422 is equal to the width D2 of the second light transmission region 34, and the interval W11 between the second support posts 424 is equal to the width D1 of the first light transmission region 32. Since the width D1 of the first light transmission region 32 is wider than the width D2 of the second light transmission region 34, the interval W11 between the second support posts 424 (i.e., the width of the space 434 between the adjacent second support posts 422) is wider than the interval W21 between the first support posts 422 (i.e., the width of the space 432 between the adjacent first support posts 422).

At step S102, as shown in fig. 10, the gaps between the pillars 420 of the mold 400 are filled with a light-transmitting resin 450. The filled light-transmitting resin 450 is defoamed. The light transmitting resin 450 is, for example, a thermosetting silicone resin.

At step S104, as shown in fig. 11, the first main surface 10a of the first light transmissive substrate 10 is pressed against the second support posts 424 and the light transmissive resin 450 exposed from between the second support posts 424.

At step S106, the light transmissive resin 450 pressed against the first main surface 10a of the first light transmissive substrate 10 is heated and cured.

In step S108, as shown in fig. 12, the mold 400 is released from the cured light transmissive resin 450 to form the light transmissive layer 60 on the first main surface 10a of the first light transmissive substrate 10. Each light transmissive layer 60 includes a first light transmissive layer 62 having a shape corresponding to the space 434 between adjacent second struts 424, and a second light transmissive layer 64 having a shape corresponding to the shape of the space 432 between adjacent first struts 422. Since the shape of the space 434 between the adjacent second support posts 424 corresponds to the shape of the first light transmission region 32 of the beam direction control element 100 and the space 432 between the adjacent first support posts 422 corresponds to the shape of the second light transmission region 34 of the beam direction control element 100, in this step, the light transmission layer 60 corresponding to the light transmission region 30 of the beam direction control element 100 is formed on the first main surface 10a of the first light transmission substrate 10.

At step S110, as shown in fig. 13, the first main surface 20a of the second light transmissive substrate 20 is opposed to the first main surface 10a of the first light transmissive substrate 10, and the second light transmissive substrate 20 is press-fitted onto the light transmissive layer 60.

At step S112, the gaps between the light-transmitting layers 60 are filled with the light-transmitting dispersion medium 52 in which the electrophoretic particles 54 are dispersed. Thus, the light absorbing regions 40 (the first light absorbing region 42 and the second light absorbing region 44) are formed. The light absorbing region 40 is sealed with an adhesive.

As described above, the beam direction control element 100 can be manufactured. In the present embodiment, the portion (first light transmitting layer 62) corresponding to the first light transmitting regions 32 arranged at narrow intervals (width D3 of the first light absorbing regions 42) is formed by the second struts 424 of the mold 400 formed at wide intervals W11. Accordingly, the beam direction control element 100 can be easily manufactured.

As described above, the height H1 of the first light transmission region 32 forming the first light absorption region 42 is lower than the height H2 of the second light transmission region 34, and the width D1 of the first light transmission region 32 is wider than the width D2 of the second light transmission region 34. Accordingly, by narrowing the width D3 of the first light absorbing region 42 in which the electrophoretic particles 54 are collected in the first wide field mode (a state in which the angular distribution of the emitted light is wide), the aperture ratio of the beam direction control element 100 in the first wide field mode can be increased, and the transmittance of the beam direction control element 100 in the first wide field mode can be increased. Further, since the width D1 of the first light transmission region 32 is wider, the adhesiveness between the first light transmission substrate 10 and the first light transmission region 32 (light transmission layer) is improved, so that the durability of the beam direction control element 100 can be improved.

Example 2

In the first wide field-of-view mode of embodiment 1, only the first light absorbing region 42 serves as a light absorbing layer. In a state where the angular distribution of the emitted light in the beam direction control element 100 is wide, a part of the first light absorbing region 42 and the second light absorbing region 44 may function as a light absorbing layer. Hereinafter, a state in which a portion of the first light absorbing region 42 and the second light absorbing region 44 functions as a light absorbing layer is referred to as a second wide field-of-view mode. Other configurations of this embodiment are the same as those of embodiment 1 except for the region serving as the light absorbing layer.

In the second wide field of view mode, a predetermined second voltage lower than the predetermined first voltage in the first wide field of view mode is applied to the electrophoretic particles 54. Accordingly, as shown in fig. 14, the electrophoretic particles 54 are collected on the first light-transmitting substrate 10 side, and the regions 46 of the first light-absorbing region 42 and the second light-absorbing region 44 on the first light-absorbing region 42 side serve as light-absorbing layers.

In the second wide field mode, since the electrophoretic particles 54 are also collected in the first light absorbing region 42 located on the first light transmitting substrate 10 side, the Optical Density (OD) value of the region 46 of the second light absorbing region 44 is low. Thus, a portion of the light 710 incident on the region 46 of the second light absorbing region 44 is transmitted through the region 46 of the second light absorbing region 44 and emitted from the beam direction control element 100. Therefore, in the second wide field of view mode, the beam direction control element 100 hardly limits the viewing angle of the display device 300 as in the first wide field of view mode. Since a part of the light 710 incident on the region 46 of the second light absorbing region 44 is also emitted from the beam direction control element 100, the transmittance of the beam direction control element 100 in the second wide field of view mode is higher than that of the comparative example in which the light absorbing region 40 is formed of only the second light absorbing region 44, as shown in fig. 15.

As described above, by applying a predetermined second voltage lower than the predetermined first voltage to the electrophoretic particles 54, the electrophoretic particles 54 are collected on the first light-transmitting substrate 10 side, which makes it possible to increase the transmittance of the beam direction control element 100 also in the second wide field-of-view mode (state in which the angular distribution of emitted light is wide) in which the first light absorption region 42 and a part (region 46) of the second light absorption region 44 serve as light absorption layers.

Example 3

In embodiment 1 and embodiment 2, the second light transmission region 34 of the beam direction control element 100 has a rectangular parallelepiped shape, and the second light transmission region 34 has a rectangular shape when viewed in cross section on the XZ plane. The second light transmission region 34 may have another shape when viewed in cross section on the XZ plane.

For example, as shown in fig. 16, the second light transmission region 34 may have a trapezoidal shape (tapered shape) when viewed in cross section on the XZ plane. In the present embodiment, the second light transmission region 34 has a trapezoidal shape in which the width D2b of the-Z side is wider than the width D2a of the +z side. For example, the width D2b is 40 μm, and the width D2a is 30 μm to 36 μm. Other dimensions of the light transmission region 30 are the same as those in the example of embodiment 1.

In the present embodiment, since the width D2b of the-Z side of the second light transmission region 34 is wider than the width D2a of the +z side of the second light transmission region 34, the width of the second light absorption region 44 decreases toward the first light absorption region 42. Accordingly, the electrophoretic particles 54 can be easily collected in the first light absorbing region 42 located at the-Z side.

Example 4

In embodiment 1 and embodiment 2, the first light transmission region 32 of the beam direction control element 100 has a rectangular parallelepiped shape, and the first light transmission region 32 has a rectangular shape when viewed in cross section on the XZ plane. The first light transmission region 32 may have another shape when viewed in cross section on the XZ plane.

For example, as shown in fig. 17, the first light transmission region 32 may have a trapezoidal shape (tapered shape) when viewed in cross section on the XZ plane. In the present embodiment, the first light transmission region 32 has a trapezoidal shape in which the width D1b of the-Z side is wider than the width D1a of the +z side. For example, the width D1a is 45 μm, and the width D1b is 47 μm. For example, the width D3a of the +z side of the first light absorption region 42 is 5 μm, and the width D3b of the-Z side of the first light absorption region 42 is 3 μm. Other dimensions of the light transmission region 30 are the same as those in the example of embodiment 1.

In the present embodiment, since the width D1b of the-Z side of the first light transmission region 32 is wider than the width D1a of the +z side of the first light transmission region 32, the electrophoretic particles 54 can be easily collected in the first light absorption region 42.

Example 5

In one example of embodiment 1, the ratio of the height H1 (25 μm) of the first light transmissive region 32 to the height H2 (120 μm) of the second light transmissive region 34 is 1:4.8. In the beam direction control element 100 of embodiments 1 to 4, the ratio of the height H1 of the first light transmission region 32 to the height H2 of the second light transmission region 34 is preferably 1:2.6 or more.

For example, when the beam direction control element 100 of embodiment 1 is observed in an XZ section, when refraction of light in the first light transmissive substrate 10 and the second light transmissive substrate 20 is ignored, the maximum emission angle θ1 of light emitted from the beam direction control element 100 with respect to the +z direction is represented by fig. 18 and the following formula 2. In the following formula 2, n represents the refractive index of the light transmission region 30, and θ2 represents the angle of light incident on the beam direction control element 100 with respect to the +z direction.

Fig. 19 shows the relationship between the height H2 of the second light transmission region 34 and the maximum emission angle θ1 calculated according to the above formula 2 when the height H1 of the first light transmission region 32 is 25 μm, the width D1 of the first light transmission region 32 is 45 μm, and the width D2 of the second light transmission region 34 is 40 μm (similar to one example of embodiment 1). As shown in fig. 19, when the refractive index n of the light transmission region 30 is 1.5 and the height H2 of the second light transmission region 34 is equal to or greater than 65 μm (i.e., the ratio of the height H1 of the first light transmission region 32 to the height H2 of the second light transmission region 34 is set to 1:2.6), the maximum emission angle θ1 may be set to be equal to or less than 40 °. Accordingly, when the refractive index n of the light transmission region 30 is 1.5 and the ratio of the height H1 of the first light transmission region 32 to the height H2 of the second light transmission region 34 is equal to or less than 1:2.6, the viewing angle of the display device 300 in the horizontal direction may be equal to or less than 80 °.

Example 6

In embodiment 1, a mold is used to manufacture the beam direction control element 100. The beam steering element 100 may be fabricated using photolithographic techniques.

Fig. 20 is a flowchart showing a method for manufacturing the beam direction control element 100 of the present embodiment. The method for manufacturing the beam direction control element 100 of the present embodiment includes: a step of forming a light shielding layer 502 at predetermined intervals W1 on the first main surface 10a of the first light transmissive substrate 10 (step S200), a step of stacking a first layer 504 made of a light transmissive material having photosensitivity at a predetermined first thickness D51 (step S202), a step of exposing the first layer 504 from the first light transmissive substrate 10 side (step S204), and a step of stacking a second layer 506 made of a light transmissive material having photosensitivity on the exposed first layer 504 at a predetermined second thickness D52 thicker than the predetermined first thickness D51 (step S206).

The method for manufacturing the beam direction control element 100 of the present embodiment further includes: a step of exposing a region 506a of the second layer 506 located between the light-shielding layers 502 from the second layer 506 side with a width D22 narrower than a predetermined interval W1 between the light-shielding layers 502 (step S208), a step of developing the exposed first layer 504 and the exposed second layer 506 and forming a plurality of light-transmitting layers 60 on the first main surface 10a of the first light-transmitting substrate 10 (step S210), and a step of press-fitting the second light-transmitting substrate 20 onto the plurality of light-transmitting layers 60 (step S212), and a step of filling a light-transmitting dispersion medium 52 in which the electrophoretic particles 54 are dispersed between the light-transmitting layers 60 (step S214).

At step S200, as shown in fig. 21, a plurality of light shielding layers 502 are formed on the first main surface 10a of the first light transmissive substrate 10. The light shielding layer 502 is arranged in the X direction. The light shielding layer 502 blocks light used to expose light transmissive materials forming the first layer 504 and the second layer 506. The light shielding layer 502 is made of chromium, aluminum, or the like. The light shielding layers 502 are formed at predetermined intervals W1, and each has a width D32 when viewed in XZ section. The predetermined interval W1 is equal to the width D1 of the first light transmission region 32 of the beam direction control element 100. The width D32 is equal to the width D3 of the first light absorbing regions 42, i.e., the interval between the first light transmitting regions 32. The predetermined interval W1 refers to an interval between side surfaces of the adjacent light shielding layers 502.

At step S202, a first layer 504 made of a light transmissive material is stacked on the first main surface 10a of the first light transmissive substrate 10 at a predetermined first thickness D51. The light transmissive material has photosensitivity. As shown in fig. 22, a first layer 504 is formed on the first main surface 10a of the first light-transmitting substrate 10 so as to cover the light-shielding layer 502. The predetermined first thickness D51 is equal to the height H1 of the first light transmitting region 32 and the first light absorbing region 42. The light-transmitting material having photosensitivity is SU-8, for example.

At step S204, first, the stacked first layers 504 are pre-baked (at 95 ℃ for 3 hours) so as to remove the solvent included in the stacked first layers 504. Subsequently, as shown in fig. 23, the first layer 504 is exposed from the first light-transmitting substrate 10 side without using a mask. Since the thickness D51 of the first layer 504 is equal to the height H1 of the first light transmission region 32 and the first light absorption region 42, and the light shielding layers 502 each having the width D32 equal to the width D3 of the first light absorption region 42 are formed at intervals W1 equal to the width D1 of the first light transmission region 32 of the beam direction control element 100, the region of the beam direction control element 100 corresponding to the first light transmission region 32 is exposed.

At step S204, after the first layer 504 is exposed, a post-exposure bake (PEB) process (25 minutes at 95 ℃) is performed.

At step S206, as shown in fig. 24, a second layer 506 made of a light transmissive material is stacked on the exposed first layer 504 at a predetermined second thickness D52. The light transmissive material forming the second layer 506 has photosensitivity. The light transmissive material forming the second layer 506 and the light transmissive material forming the first layer 504 may be the same or different from each other. The predetermined second thickness D52 is equal to the height H2 of the second light transmitting region 34 and the second light absorbing region 44, and is thicker than the predetermined first thickness D51.

At step S208, first, the stacked second layer 506 is prebaked (30 minutes at 95 ℃). Subsequently, as shown in fig. 25, when viewed in a plan view, a region 506a of the second layer 502 located between the light shielding layers 502 is exposed from the second layer 506 side by a width D22 by using a mask M. The width D22 is equal to the width D2 of the second light transmission region 34 and is narrower than the predetermined interval W1 of the light shielding layer 502. Since the thickness D52 of the second layer 506 is equal to the height H2 of the second light transmitting region 34 and the second light absorbing region 44, and the width D22 is equal to the width D2 of the second light transmitting region 34, the region of the beam direction control element 100 corresponding to the second light transmitting region 34 is exposed.

At step S208, after the second layer 506 is exposed, a PEB process (25 minutes at 95 ℃) is performed.

At step S210, the exposed first layer 504 and the exposed second layer 506 are developed with a developer. After development, the first layer 504 and the second layer 506 were rinsed with a rinse solution and post-baked (30 minutes at 150 ℃). Accordingly, as shown in fig. 26, a plurality of light transmissive layers 60 are formed on the first main surface 10a of the first light transmissive substrate 10.

In the present embodiment, at step S204, the region of the first layer 504 corresponding to the first light transmission region 32 is exposed, and at step S208, the region of the second layer 506 corresponding to the second light transmission region 34 is exposed. Therefore, in this step, the light-transmitting layer 60 of the beam direction control element 100 corresponding to the light-transmitting region 30 is formed on the first main surface 10a of the first light-transmitting substrate 10.

Steps S212 and S214 of the present embodiment are the same as steps S110 and S112 of embodiment 1.

By the above, the beam direction control element 100 can be manufactured. At step S204 of the present embodiment, the region of the first layer 504 corresponding to the first light transmissive region 32 is exposed from the first light transmissive substrate 10 side. Accordingly, the first layers 504 are exposed through the light shielding layers 502, each light shielding layer 502 having a width D32 equal to the interval between the first light transmission regions 32 (the width D3 of the first light absorption region 42), so that portions corresponding to the first light transmission regions 32 and arranged at narrow intervals (the width D3 of the first light absorption region 42) can be easily formed, and the beam direction control element 100 can be easily manufactured. In the beam direction control element 100 of the present embodiment, the light shielding layer 502 is present on the first main surface 10a of the first light transmissive substrate 10. Since the light shielding layer 502 is located in the light absorbing region 40, the light shielding layer 502 does not affect the characteristics of the beam direction control element 100.

Variant examples

Although the embodiments have been described above, the present disclosure may be modified in various ways without departing from the spirit of the present disclosure.

For example, the first light transmissive substrate 10 and the second light transmissive substrate 20 may each be made of a light transmissive resin. The electrophoretic particles 54 may be positively charged.

In this embodiment, the mold 400 is produced using known photolithographic techniques. The mold 400 may be produced by cutting metal (e.g., silicon). The mold 400 may be a nickel (Ni) mold, a copper (Cu) mold, or the like.

In this embodiment, post 420 is made of chemically amplified photoresist SU-8. The post 420 may be made of another resist. For example, post 420 may be made of a negative resist: KMPR (trade name, nippon Kayaku co., ltd.). The post portions 420 may also be formed using a dry film resist.

In the present embodiment, a thermosetting silicone resin is used as the light transmissive resin 450. The light transmitting resin 450 may be a thermosetting epoxy resin, a thermosetting acrylic resin, or the like.

The light transmissive resin 450 may also be an Ultraviolet (UV) curable resin (silicone, epoxy, acrylic, etc.). When a UV curable resin is used as the light transmissive resin 450, the light transmissive resin 450 is irradiated with UV light from the first light transmissive substrate 10 side or the second light transmissive substrate 20 side, so that the light transmissive resin 450 is cured (step S106).

In the present embodiment, the light 710 incident on the beam direction control element 100 is incident on the beam direction control element 100 from the first light transmissive substrate 10 side (-Z side). As shown in fig. 27, light 710 may be incident on the beam direction control element 100 from the second light transmissive substrate 20 side (+z side). In this case, the beam direction control element 100 controls the angular distribution of the light 710 incident from the +z direction and emits the light 710 in the-Z direction.

In one example of embodiment 1, the first light absorbing region 42 may be filled with electrophoretic particles 54 to a height of 21.8 μm of H1 (25 μm) thereof. In the first wide field mode, the first light absorbing region 42 may be filled with the electrophoretic particles 54 to a height equal to or less than the height H1 thereof.

In this embodiment, the beam direction control element 100 operates in a first wide field of view mode, a second wide field of view mode, and a narrow field of view mode. The beam steering element 100 may operate in a first wide field of view mode and a narrow field of view mode. The beam steering element 100 may also operate in a second wide field of view mode and a narrow field of view mode.

When the beam direction control element 100 operates in the second wide field mode and the narrow field mode, the electrophoretic particles 54 dispersed in the light transmissive dispersion medium 52 may have a concentration or volume of filling the regions 46 of the first and second light absorbing regions 42 and 44 with the electrophoretic particles 54 in a state where a voltage equal to or greater than a predetermined second voltage is applied.

In embodiment 3, the second light transmission region 34 has a trapezoidal shape when viewed in XZ section. In embodiment 4, the first light transmission region 32 has a trapezoidal shape. The first light-transmitting region 32 and the second light-transmitting region 34 may each have a trapezoidal shape when viewed in XZ cross section.

Although the side surfaces of the first light transmission regions 32 in embodiments 1 to 4 are planar, the side surfaces of the first light transmission regions 32 may be curved as shown in fig. 28. For example, the width D1b on the-Z side of the first light transmitting region 32 is 47 μm, and the width D3b on the-Z side of the first light absorbing region 42 is 3 μm. The corner 32b of the first light transmission region 32 may be curved as shown in fig. 29.

In the first light transmission region 32 having a trapezoidal shape, as shown in fig. 30, the width D1b on the-Z side may be wider than the width D1a on the +z side, and the width D1a on the +z side of the first light transmission region 32 may be equal to the width (-width on the Z side) D2 of the second light transmission region 34. Accordingly, the width D1 of the first light transmission region 32 continuously widens from the width (-width on the Z side) D2 of the second light transmission region 34 toward the first light transmission substrate 10 to the width D1b on the-Z side. Since the width D1 of the first light-transmitting region 32 continuously widens from the width D2 of the second light-transmitting region 34 toward the first light-transmitting substrate 10 to the width D1b on the-Z side, in the first wide field-of-view mode, it is possible to prevent a portion of the electrophoretic particles 54 from remaining on the step portion 38 (the upper surface 32a of the first light-transmitting region 32) between the first light-transmitting region 32 and the second light-transmitting region 34, as shown in fig. 31. By suppressing the remaining electrophoretic particles 54, the transmittance of the beam direction control element 100 in the first wide field mode can be further improved.

It is sufficient if the stepped portion 38 between the first light transmission region 32 and the second light transmission region 34 is not present. For example, the side surface of the first light transmission region 32 in the modification described above (fig. 30) is planar, but the side surface of the first light transmission region 32 may be curved as shown in fig. 32 and 33. Also in the present modification, the width D1b on the-Z side is wider than the width D1a on the +z side, and the width D1a on the +z side of the first light transmission region 32 is equal to the width (-Z side width) D2 of the second light transmission region 34. The width D1 of the first light-transmitting region 32 continuously widens from the width (-width on the Z side) D2 of the second light-transmitting region 34 toward the first light-transmitting substrate 10 to a width D1b on the-Z side. Also in the present modification, similar to the modification described above, the step portion 38 between the first light transmission region 32 and the second light transmission region 34 can be eliminated, and the remainder of the electrophoretic particles 54 can be suppressed. By suppressing the remaining electrophoretic particles 54, the transmittance of the beam direction control element 100 in the first wide field mode can be further improved.

Further, as shown in fig. 34, the stepped portion 38 between the first light transmission region 32 and the second light transmission region 34 may also be eliminated by cutting the corner 32b of the first light transmission region 32 into a curved shape. Also in the present modification, the width D1 of the first light-transmitting region 32 continuously widens from the width (-width on the Z side) D2 of the second light-transmitting region 34 toward the first light-transmitting substrate 10 to the width D1b on the-Z side. Also in the present modification, the remaining of the electrophoretic particles 54 can be suppressed. By suppressing the remaining electrophoretic particles 54, the transmittance of the beam direction control element 100 in the first wide field mode can be further improved.

As shown in fig. 35, the display device 300 may include a beam direction control element 100, a transmissive liquid crystal display panel 215, and a backlight 220. The backlight 220 is disposed at an opposite side of the display surface of the transmissive liquid crystal display panel 215, and supplies light to the transmissive liquid crystal display panel 215. The beam direction control element 100 is disposed between the transmissive liquid crystal display panel 215 and the backlight 220, and controls the angular distribution of light supplied from the backlight 220 to the transmissive liquid crystal display panel 215.

As shown in fig. 36, the beam direction control element 100 may be disposed on the display surface of the transmissive liquid crystal display panel 215.

For purposes of explanation, some example embodiments were described above. Although the foregoing discussion has set forth specific embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

Claims

1. A beam steering element, comprising:

a first light-transmitting substrate including a first light-transmitting electrode on a main surface;

a second light-transmitting substrate facing the first light-transmitting substrate and including a second light-transmitting electrode on a main surface facing a main surface of the first light-transmitting substrate;

a plurality of light-transmitting regions arranged in a predetermined direction and interposed between the first light-transmitting substrate and the second light-transmitting substrate;

a plurality of light absorbing regions located between the light transmitting regions;

an electrophoretic particle absorbing light, which is dispersed in the light-transmitting dispersion medium and has a dispersed state changed by an applied voltage, wherein

Each of the light transmitting regions includes: a first light-transmitting region extending perpendicularly to the main surface of the first light-transmitting substrate from the main surface of the first light-transmitting substrate toward the second light-transmitting substrate, and a second light-transmitting region extending perpendicularly to the main surface of the first light-transmitting substrate from the upper surface of the first light-transmitting region toward the second light-transmitting substrate,

Each of the light absorbing regions includes a first light absorbing region located between the first light transmitting regions and a second light absorbing region located between the second light transmitting regions,

the width of the first light-transmitting region is wider than the width of the second light-transmitting region when viewed in a section including the predetermined direction and perpendicular to the main surface of the first light-transmitting substrate.

2. The beam direction control element according to claim 1, wherein the electrophoretic particles are collected in the first light absorbing region when a predetermined first voltage is applied between the first light transmitting electrode and the second light transmitting electrode.

3. The beam direction control element according to claim 1, wherein the electrophoretic particles are collected on one side of the first light transmissive substrate when a predetermined second voltage is applied between the first light transmissive electrode and the second light transmissive electrode.

4. The beam direction control element according to claim 1, wherein a ratio of a height of the first light transmission region from a main surface of the first light transmission substrate to a height of the second light transmission region from an upper surface of the first light transmission region is 1:2.6 or more.

5. The beam direction control element according to claim 1, wherein a width of the first light transmissive region continuously widens from a width of the second light transmissive region toward the first light transmissive substrate.

6. A display device, comprising:

a beam direction control element according to any one of claims 1 to 5; and

the display panel is provided with a display screen,

7. A display device, comprising:

a beam direction control element according to any one of claims 1 to 5;

a transmissive liquid crystal display panel; and

a backlight disposed at an opposite side of a display surface of the transmissive liquid crystal display panel and providing light to the transmissive liquid crystal display panel,

8. A method for manufacturing a beam steering element, the method comprising:

preparing a mold including a mold substrate, a plurality of first pillars disposed on a main surface of the mold substrate perpendicularly to the main surface and arranged in a predetermined direction, and a second pillar disposed on an upper surface of each of the plurality of first pillars perpendicularly to the main surface of the mold substrate;

Filling the mold with a light-transmitting resin;

pressing a main surface of a first light-transmitting substrate against the second support posts and the light-transmitting resin exposed from between the second support posts, the first light-transmitting substrate including a first light-transmitting electrode on the main surface of the first light-transmitting substrate;

curing the light transmissive resin pressed against the main surface of the first light transmissive substrate;

demolding the mold from the cured light-transmitting resin, and forming a plurality of light-transmitting layers on the main surface of the first light-transmitting substrate, the plurality of light-transmitting layers including a first light-transmitting layer having a shape corresponding to the shape of the space between the adjacent second pillars, and a second light-transmitting layer having a shape corresponding to the shape of the space between the adjacent first pillars;

press-fitting a second light-transmitting substrate facing the first light-transmitting substrate onto the plurality of light-transmitting layers, the second light-transmitting substrate including a second light-transmitting electrode on a main surface facing a main surface of the first light-transmitting substrate; and

filling a light-transmitting dispersion medium including dispersed electrophoretic particles that absorb light and have a dispersion state changed by an applied voltage between the light-transmitting layers, wherein

The height of the space between the adjacent second pillars is lower than the height of the space between the adjacent first pillars, and

the width of the space between the adjacent second pillars is wider than the width of the space between the adjacent first pillars when viewed in a section including the predetermined direction and perpendicular to the main surface of the mold substrate.

9. A method for manufacturing a beam steering element, the method comprising:

forming a light shielding layer on a main surface of a first light transmitting substrate including a first light transmitting electrode on the main surface at predetermined intervals;

stacking a first layer having a predetermined first thickness, which is made of a light-transmitting material having photosensitivity and covers the light-shielding layer, on a main surface of the first light-transmitting substrate;

exposing the first layer from one side of the first light transmissive substrate;

stacking a second layer having a predetermined second thickness thicker than the predetermined first thickness on the exposed first layer, the second layer being made of a light-transmitting material having photosensitivity;

exposing a region of the second layer located between the light-shielding layers with a width narrower than a predetermined interval between the light-shielding layers when viewed in a plan view from one side of the second layer;

Developing the exposed first layer and the exposed second layer and forming a plurality of light transmissive layers on the first major surface of the first light transmissive substrate;

a light-transmitting dispersion medium including dispersed electrophoretic particles that absorb light and have a dispersion state changed by an applied voltage is filled between the light-transmitting layers.